5 Answers
5

You want to format the drive using Fat32, which is most readable. I'm not sure about the Mac procedure, but to format the drive in Windows you right click on it in (My) Computer and select "Format..." Set the file system to Fat32 (it should be the default, but you should make sure). Also make sure that "Quick Format" is UNselected, as it does not erase the data. Then click OK and it will start formatting the drive. It will warn you, but I'm going to reiterate (preiterate?) DO NOT REMOVE THE DRIVE AT THIS TIME. Also be aware that this will remove all the files, though not necessarily securely.

Also, depending on the sensivitity of the information and the people you are afraid might read it, you might want to do further erasing procedures. I know that the Mac allows you to delete files securely. You need to do this BEFORE reformatting the drive, or there will be no files to erase securely.

Fat32 is simplest but remember that it cannot store files larger than 4Gb.
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MarkJul 31 '09 at 20:48

1

True, it doesn't work with large files, but it's the most recognized by OSes.
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Daniel HJul 31 '09 at 22:58

The warning about not removing the drive is pretty unnecessary. If he does, the only bad thing that will happen is that the file system on the stick will be broken, i.e. he will have to format it again and "lose" all of the non-existent data, but there will not be any kind of permanent damage.
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Jan SchejbalMar 13 '13 at 15:22

If you want to use the drive with Windows, you can choose between FAT32 or NTFS. FAT32 gives great compatibility with about everything, but cannot store files larger than 4 GB. NTFS can be read under OS X by default starting with 10.3 (from 2003), and read/write access is possible since 10.6 using an unsupported, hidden function (or external tools). Source

To wipe the disk, I would suggest to use a separate disk wiping/secure erasure utility, or simply Linux with the "dd" command. Make sure to erase the entire stick, not just the files, to avoid residue. This will reliably prevent recovery using standard recovery tools.

If you are afraid that someone might disassemble the stick and scrape data off using special hardware (or undocumented low-level interfaces), the only reasonable way to "wipe" it securely to prevent that is physical destruction of the flash module.